<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //创建一个正则,小写字母三个以上
        const reg = /^[a-z]{3,}$/i
        console.log(reg.test("abcdef"));//true
        console.log(reg.test("abcdef123"));//false
        console.log(reg.test("ABCDEF"));//true
        console.log(reg.test("abcDEF"));//true
    </script>
</body>
</html>